JP2016134744A - Satellite broadcast system, receiver, transmitter, reception method, and transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce generation of a reception error caused by control of a broadcast satellite's radiation pattern.SOLUTION: A satellite broadcast system 1 comprises: a broadcast satellite 20 for relaying and radiating a broadcast wave on which phase modulation has been performed; a transmitter 12 for controlling the broadcast satellite's radiation pattern; and a receiver 32 that generates a reference signal from a reception signal of a reception antenna 31 for receiving a broadcast wave and demodulates the reception signal on the basis of a phase of the generated reference signal. The transmitter 12, in the case of switching the broadcast satellite's radiation pattern, generates phase information on a phase that corresponds to a radiation pattern after switching and is of a broadcast wave to be received in a reception region, and a switching advance notice signal showing timing of radiation pattern switching. The receiver 32 acquires the phase information and switching advance notice signal generated by the transmitter 12; and controls, at the timing shown by the acquired switching advance notice signal on the basis of the acquired phase information, a phase of the reception antenna 31's reception signal or the reference signal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a satellite broadcasting system, a receiver, a transmitter, a reception method, and a transmission method.

  A satellite broadcasting system (21 GHz band satellite broadcasting system) using a frequency of 21 GHz band (21.4 to 22.0 GHz) has been studied. In general, the 21 GHz band satellite broadcasting system has a problem that a sufficient service time rate may not be ensured because radio wave attenuation due to rain (rain attenuation) is larger than that of the current 12 GHz band satellite broadcasting system.

  Therefore, an array-fed imaging reflector antenna that can switch the radiation pattern is mounted on a broadcasting satellite as a transmission antenna, and the power that is radiated throughout the country is irradiated with increased power while irradiating the entire country with uniform power. Techniques for forming beams (rain attenuation compensation techniques) have been studied (for example, see Non-Patent Document 1).

  Patent Document 1 discusses a technique for preventing an excessive input of a broadcast wave to a receiver due to switching of a radiation pattern of a broadcast satellite.

JP 2004-274640 A

Nagasaka et al., “Array-fed Imaging Reflector Antenna Experimental Model for 21 GHz Band Broadcasting Satellites”, Eijitsu Technical Report, Vol. 36 No. 37, pp. 17-20, September 2012

  In general, phase modulation is used to modulate digital satellite broadcast waves. Demodulation of a phase-modulated signal requires a signal that serves as a phase reference (reference signal), and the reference signal is generated from the received broadcast wave. This technology is referred to as carrier regeneration, and has been put into practical use in the current 12 GHz band satellite broadcasting system and the like. However, the generation of the reference signal is based on the assumption that the broadcast wave or TMCC (Transmission Multiplexing Configuration Control) included in the broadcast wave is correctly demodulated.

  As described above, in the 21 GHz band satellite broadcasting system, switching the radiation pattern is being studied. Here, when the radiation pattern is switched, the phase of the received signal of the receiver may change.

  FIG. 6 is a diagram showing an example of a radiation pattern of a broadcasting satellite. FIG. 6A shows a radiation pattern in which power is uniformly radiated nationwide (national uniform pattern), and FIG. A radiation pattern (Osaka boost pattern) in which a boost beam is formed is shown. FIG. 7 is a diagram showing the phase distribution of broadcast waves (received signals) received in each reception area. FIG. 7 (a) shows the phase distribution in a nationwide uniform pattern, and FIG. 7 (b) shows Osaka. The phase distribution in a boost pattern is shown.

  When the radiation pattern is switched from the nationwide uniform pattern to the Osaka boosting pattern, as shown in FIG. 7, in Tokyo, the phase of the received signal changes by about 8.5 degrees from about 158.7 degrees to 167.2 degrees. Yes. As described above, when the radiation pattern of the broadcast satellite is switched, the phase of the received signal changes discretely depending on the reception area. If the phase of the received signal changes discretely, the broadcast wave or TMCC cannot be correctly demodulated at the receiver, and carrier reproduction cannot be performed. Therefore, there is a problem that a reception error occurs.

  The technique disclosed in Patent Document 1 is a technique for preventing an excessive input due to the formation of an intensifying beam, and does not correspond to a change in phase of a received signal due to switching of a radiation pattern.

  An object of the present invention is to provide a satellite broadcasting system, a receiver, a transmitter, a receiving method, and a transmitting method that can solve the above-described problems and reduce the occurrence of reception errors due to the control of the radiation pattern of a broadcasting satellite. It is in.

  In order to solve the above problems, a satellite broadcasting system according to the present invention includes a broadcasting satellite that relays and radiates a phase-modulated broadcasting wave, a transmitter that controls a radiation pattern of the broadcasting satellite, and a radiation that is radiated from the broadcasting satellite. And a receiver that demodulates the received signal based on the phase of the generated reference signal, and that generates a reference signal from a received signal of a receiving antenna that receives the broadcast wave. When switching the pattern, the phase information related to the phase of the broadcast wave received in the reception area corresponding to the radiation pattern after the switching, and a switching notice signal indicating the timing of switching the radiation pattern, and the receiver The phase information and the switching notice signal created by the transmitter are acquired, and at the timing indicated in the acquired switching notice signal, the acquired phase information is acquired. Based on, to control the phase of the received signal or the reference signal of the receiving antenna.

  In order to solve the above problems, a receiver according to the present invention demodulates a received signal based on a phase of a reference signal obtained from a received signal of a receiving antenna that receives a broadcast wave radiated from a broadcasting satellite. The phase information regarding the phase of the received signal in the broadcast wave reception area corresponding to the radiation pattern after switching, generated by the transmitter that controls the radiation pattern of the broadcasting satellite, and the timing for switching the radiation pattern. And a phase control unit that controls the phase of the reception signal of the reception antenna or the reference signal based on the acquired phase information at a timing indicated by the acquired switching notification signal.

  Further, in the receiver according to the present invention, based on an orthogonal demodulation circuit that performs orthogonal demodulation on the reception signal of the reception antenna using the reference signal, and an IQ signal generated by orthogonal demodulation by the orthogonal demodulation circuit, It is preferable that the carrier reproduction circuit generates the reference signal, and the phase control unit causes the carrier reproduction circuit to control the phase of the reference signal based on the phase information.

  In the receiver according to the present invention, a high-frequency amplifier that amplifies the reception signal of the reception antenna, a local oscillator that outputs a local oscillation signal having a frequency corresponding to the selected broadcast station, and amplification by the high-frequency amplifier And a mixer for synthesizing the local oscillation signal and the local oscillation signal, the high frequency amplification unit is provided with a phase shifter for shifting the phase of the reception signal, and the phase control unit Based on this, it is preferable to control the phase shift amount of the received signal by the phase shifter.

  In the receiver according to the present invention, a high-frequency amplifier that amplifies the reception signal of the reception antenna, a local oscillator that outputs a local oscillation signal having a frequency corresponding to the selected broadcast station, and the local oscillator output A phase shifter that shifts the phase of the local oscillation signal, and a mixer that synthesizes the signal amplified by the high frequency amplification unit and the local oscillation signal shifted by the phase shifter, and the phase control unit includes: Preferably, the phase shift amount of the local oscillation signal by the phase shifter is controlled based on the phase information.

  Further, in the receiver according to the present invention, it is preferable that the switching notice signal and the phase information are acquired via a predetermined communication path that does not pass through the broadcasting satellite or does not pass through the broadcasting satellite. .

  In order to solve the above problems, a transmitter according to the present invention is a transmitter that controls a radiation pattern of a broadcast satellite that relays and emits a phase-modulated broadcast wave, and switches the radiation pattern of the broadcast satellite. A control unit that creates phase information related to a phase of a broadcast wave received in a reception area corresponding to the radiation pattern after the switching, and a switching notice signal indicating a timing for switching the radiation pattern; and A communication unit that transmits the created phase information and switching notice signal to the broadcasting satellite, or transmits to a receiver that demodulates the broadcasting wave via a predetermined communication path that does not pass through the broadcasting satellite, Have.

  In the transmitter according to the present invention, it is preferable that the control unit causes the communication unit to transmit the switching notice information only a specified time before switching the radiation pattern of the broadcasting satellite.

  In order to solve the above problems, a receiving method according to the present invention includes a receiver that demodulates a received signal based on a phase of a reference signal obtained from a received signal of a receiving antenna that receives a broadcast wave radiated from a broadcasting satellite. And a phase information relating to a phase of a broadcast wave received in a reception area corresponding to the radiation pattern after switching, generated by a transmitter for controlling the radiation pattern of the broadcasting satellite, and the radiation pattern. A step of obtaining a switching notice signal indicating a switching timing, and a step of controlling the phase of the reception signal or the reference signal of the receiving antenna based on the obtained phase information at the timing indicated by the obtained switching notice signal And including.

  In order to solve the above problem, a transmission method according to the present invention is a transmission method in a transmitter for controlling a radiation pattern of a broadcast satellite that relays and emits a phase-modulated broadcast wave, and the radiation of the broadcast satellite When switching patterns, creating the phase information related to the phase of the broadcast wave received in the reception area corresponding to the radiation pattern after the switching, and the switching notice signal indicating the timing for switching the radiation pattern, and the creation Transmitting the phase information and the switching notice signal to the broadcasting satellite, or transmitting the phase information and the switching notice signal to a receiver that demodulates the broadcasting wave via a predetermined communication path that does not pass through the broadcasting satellite.

  According to the satellite broadcast system, the receiver, the transmitter, the reception method, and the transmission method according to the present invention, it is possible to solve the above-described problems and reduce the occurrence of reception errors due to the control of the radiation pattern of the broadcast satellite.

It is a figure which shows the structure of the satellite broadcasting system which concerns on one Embodiment of this invention. It is a figure which shows schematic structure of the array feeding imaging reflector antenna with which the broadcasting satellite shown in FIG. 1 is provided. It is a figure which shows an example of a principal part structure of the receiver shown in FIG. It is a figure which shows another example of a principal part structure of the receiver shown in FIG. It is a figure which shows another example of a principal part structure of the receiver shown in FIG. It is a figure which shows an example of the radiation pattern of a broadcast satellite. It is a figure which shows an example of the phase distribution of a received signal.

  Embodiments of the present invention will be described below.

  FIG. 1 is a diagram showing a configuration of a satellite broadcasting system 1 according to an embodiment of the present invention.

  A satellite broadcast system 1 shown in FIG. 1 includes a transmission system 10, a broadcast satellite 20, and a reception system 30.

  The transmission system 10 transmits a command signal for controlling the operation of the broadcast satellite 20 to the broadcast satellite 20. The transmission system 10 multiplexes and modulates a video signal, an audio signal, a control signal for the reception system 30, and the like, and transmits the multiplexed signal to the broadcast satellite 20 as a broadcast wave. Phase modulation such as BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), or 8PSK is used for modulation of the broadcast wave.

  The broadcast satellite 20 operates according to the command signal transmitted from the transmission system 10. The broadcast satellite 20 receives a broadcast wave including a video signal, an audio signal, a control signal, and the like transmitted from the transmission system 10, performs frequency conversion and amplification, and radiates it toward the earth (service area).

  The broadcast satellite 20 includes, for example, the above-described array-fed imaging reflector antenna and can switch the radiation pattern.

  FIG. 2 is a diagram showing a schematic configuration of the array-fed imaging reflector antenna 21. As shown in FIG. The array-fed imaging reflector antenna 21 shown in FIG. 2 has a plurality of (31 in FIG. 2) horn antennas 22, a feeding circuit 23, a sub-reflecting mirror 24, and a main reflecting mirror 25. The number of horn antennas 22 is an example.

  Each of the plurality of horn antennas 22 is fed from a feeding circuit 23 and radiates radio waves. The radio waves radiated from the horn antennas 22 are combined in space and reflected by the sub-reflecting mirror 24 having an aperture diameter of 0.24 m, for example. The radio wave reflected by the sub-reflecting mirror 24 is reflected by the main reflecting mirror 25 having an opening diameter of 1.8 m, for example, and is radiated to the service area. In the array-fed imaging reflector antenna 21 shown in FIG. 2, the radiation pattern can be switched by controlling the phase of the output of each horn antenna 22.

  Referring to FIG. 1 again, the receiving system 30 receives a broadcast wave radiated from the broadcast satellite 20, performs carrier reproduction, and reproduces a video signal and an audio signal. The receiving system 30 operates according to a control signal included in the received signal.

  Next, the configuration of the transmission system 10 and the reception system 30 will be described. The broadcast satellite 20 has a configuration for radiating broadcast waves in accordance with the control of the transmission system 10, and such a configuration is well known to those skilled in the art and will not be described.

  First, the configuration of the transmission system 10 will be described.

  A transmission system 10 illustrated in FIG. 1 includes a transmission antenna 11 and a transmitter 12.

  The transmission antenna 11 transmits a command signal and a broadcast wave to the broadcast satellite 20. The broadcast wave is obtained by multiplexing and modulating a video signal, an audio signal, a control signal for the reception system 30, and the like.

  The transmitter 12 is usually a terrestrial transmitter managed by a satellite operator. The transmitter 12 can communicate with the broadcast satellite 20 via the transmission antenna 11. Further, the transmitter 12 may be able to communicate with a receiver 32 of the receiving system 30 described later via communication that does not pass through the broadcast satellite 20. The transmitter 12 includes a communication unit 13 and a control unit 14.

  The communication unit 13 can communicate with the broadcast satellite 20 via the transmission antenna 11, and transmits a command signal, a video signal, an audio signal, a control signal for the reception system 30, and the like to the broadcast satellite 20. The communication unit 13 may be communicable with the receiving system 30 via a predetermined communication path such as the Internet that does not pass through the broadcast satellite 20.

  The control unit 14 controls the operation of the entire transmitter 12. For example, the control unit 14 generates a command signal, a video signal, an audio signal, a control signal for the reception system 30, and the like. Then, the control unit 14 causes the communication unit 13 to transmit the generated command signal, video signal, audio signal, and the like to the broadcast satellite 20. In addition, the control unit 14 causes the communication unit 13 to transmit the generated control signal to the broadcast satellite 20 or to the reception system 30 via a predetermined communication path that does not pass through the broadcast satellite 20. As the command signal, for example, there is a signal instructing switching of a radiation pattern. Further, in the present embodiment, phase information related to the phase of the received signal in the broadcast wave reception area corresponding to the switched radiation pattern, a switching notice signal indicating the switching timing of the radiation pattern of the broadcast satellite 20, etc. are received. It is transmitted to the receiving system 30 as a control signal for the system 30.

  Next, the configuration of the receiving system 30 will be described.

  A reception system 30 illustrated in FIG. 1 includes a reception antenna 31 and a receiver 32.

  The receiving antenna 31 receives a broadcast wave radiated from the broadcast satellite 20.

  The receiver 32 generates a reference signal from the received signal (broadcast wave) of the receiving antenna 31 (carrier reproduction), demodulates the received signal based on the phase of the generated reference signal, and decodes a video signal, an audio signal, and the like. Make it possible. Further, the receiver 32 acquires the phase information and the switching notice signal via the broadcast satellite 20 or via a communication path not via the broadcast satellite 20. Then, the receiver 32 controls the phase of the reception signal or the reference signal of the reception antenna 31 based on the acquired phase information at the radiation pattern switching timing indicated in the acquired switching advance notice signal.

  Next, the operation of the satellite broadcasting system 1 according to this embodiment will be described.

  First, in the transmission system 10, when the radiation pattern of the broadcast satellite 20 is switched, the control unit 14 calculates the phase of the received signal in the broadcast wave reception area corresponding to the radiation pattern after switching. Note that an existing simulation method can be used for such calculation. Based on the calculation result, the control unit 14 generates phase information related to the phase of the broadcast wave received in the reception area corresponding to the radiation pattern after switching. Moreover, the control part 14 produces | generates the switch warning signal which shows the timing which switches a radiation pattern.

  Next, the control unit 14 multiplexes the generated phase information into a broadcast wave and causes the communication unit 13 to transmit to the broadcast satellite 20 or causes the communication unit 13 to pass through a predetermined communication path that does not pass through the broadcast satellite 20. The phase information generated in this way is transmitted to the receiving system 30. When phase information is transmitted via the broadcast satellite 20, the phase information is transmitted uniformly throughout Japan. On the other hand, when the phase information is transmitted via a predetermined communication path not via the broadcast satellite 20, the control unit 14 may transmit the phase information on a regional basis.

  In addition, the control unit 14 multiplexes the generated switching advance notice signal as a control signal on a broadcast wave, and causes the communication unit 13 to transmit the broadcast wave 20. Here, the control unit 14 causes the broadcast satellite 20 to transmit the switching notice signal only for the specified time (for the specified number of frames) before the actual switching of the radiation pattern. Note that the control unit 14 may cause the communication unit 13 to transmit the switching notice signal to the receiver 32 via a predetermined communication path that does not pass through the broadcast satellite 20.

  Next, the control unit 14 causes the communication unit 13 to transmit a signal instructing switching of the radiation pattern to the broadcast satellite 20 as a command signal.

  In the reception system 30, the reception antenna 31 receives broadcast waves radiated from the broadcast satellite 20.

  The receiver 32 acquires a switching notice signal included in the reception signal (broadcast wave) of the reception antenna 31. The receiver 32 acquires phase information included in the received signal or transmitted from the transmitter 12 via a predetermined communication path.

  Then, the receiver 32 controls the phase of the reception signal or the reference signal of the reception antenna 31 based on the acquired phase information at the timing indicated by the acquired switching advance notice signal. Specifically, the receiver 32 controls the phase of the received signal or the reference signal based on the phase corresponding to the installation area of the receiver 32 indicated in the phase information. By doing so, it is possible to maintain phase synchronization between the received signal and the reference signal even after the radiation pattern of the broadcasting satellite is changed. Therefore, the receiver 32 can demodulate the received signal (decode video data and audio data) even after switching the radiation pattern, and can reduce the possibility of a reception error. Even when the regional phase of the whole country is uniformly transmitted to all the receivers 32 as the phase information, the receiver 32 grasps the installation area by registering the zip code at the time of installation of the receiver 32 and the like. The position of the area can be recognized. Alternatively, the phase information of each installation area may be transmitted for each receiver 32 via a predetermined communication path.

  Next, a specific circuit configuration example of the receiver 32 will be described.

  FIG. 3 is a diagram illustrating an example of a circuit configuration of the receiver 32.

  3 includes a high-frequency circuit 301, mixers 302 and 303, A / D converters 304 and 305, route roll-off filters 306 and 307, a signal processing unit 308, a clock generation circuit 309, and the like. , A carrier regeneration circuit 310, a 90 ° phase shifter 311, a memory 312, and a phase control unit 313.

  A reception signal of the reception antenna 31 is input to the high frequency circuit 301.

  The high frequency circuit 301 amplifies a signal having a frequency corresponding to the selected broadcast station from the reception signal of the reception antenna 31 and outputs the amplified signal to the mixers 302 and 303.

  The mixer 302 mixes an output signal of the high frequency circuit 301 and a reference signal output from a carrier recovery circuit 310 described later, and outputs the mixed signal to the A / D converter 304.

  The mixer 303 mixes the output signal of the high frequency circuit 301 and the signal whose phase of the reference signal output from the carrier reproduction circuit 310 is shifted by 90 ° by the 90 ° phase shifter 311 and outputs the mixed signal to the A / D converter 305. To do.

  The mixers 302 and 303 and the 90 ° phase shifter 311 mix the modulated signal (the output signal of the high-frequency circuit 301) with each of two orthogonal signals (a signal obtained by shifting the phase of the reference signal and the reference signal by 90 °). Thus, a quadrature demodulation circuit 314 that performs quadrature modulation to generate an I component (in-phase component) signal and a Q component (quadrature component) signal is configured.

  The A / D converter 304 converts the analog signal (I signal) output from the mixer 302 into a digital signal and outputs the digital signal to the root roll-off filter 306.

  The A / D converter 305 converts the analog signal (Q signal) output from the mixer 303 into a digital signal and outputs the digital signal to the root roll-off filter 307.

  The root roll-off filter 306 performs a filtering process on the output signal of the A / D converter 304 and outputs the filtered signal to the signal processing unit 308, the clock generation circuit 309, and the carrier recovery circuit 310.

  The root roll-off filter 307 performs a filtering process on the output signal of the A / D converter 305, and outputs the filtered signal to the signal processing unit 308, the clock generation circuit 309, and the carrier recovery circuit 310.

  The signal processing unit 308 performs symbol determination on the output signals (IQ signals) of the route roll-off filters 306 and 307, and performs signal processing based on the determination value. The signal processing unit 308 outputs the switching notification signal to the phase control unit 313 when the switching notification signal is included in the broadcast wave. Further, the signal processing unit 308 stores the phase information in the memory 312 when the broadcast wave includes phase information.

  The clock generation circuit 309 generates a clock signal that defines the sampling period of the A / D converters 304 and 305 from the output signals (IQ signals) of the root roll-off filters 307 and 308, and the A / D converters 304 and 305. Output to.

  Carrier recovery circuit 310 generates a reference signal for quadrature demodulation circuit 314 to perform quadrature demodulation from the output signals of root roll-off filters 307 and 308, and outputs the reference signal to mixer 302 and 90 ° phase shifter 311.

  The 90 ° phase shifter 311 shifts the phase of the reference signal output from the carrier reproduction circuit 310 by 90 ° and outputs the result to the mixer 303.

  When phase information is output from the signal processing unit 308, the memory 312 stores the phase information. The memory 312 stores the phase information when phase information is transmitted from the transmitter 12 via a communication path that does not pass through the broadcast satellite 20.

  When the switching notice signal is output from the signal processing unit 308, the phase control unit 313 reads the phase information stored in the memory 312. Then, the phase control unit 313 is based on the phase information read from the memory 312 at the timing indicated by the switching notice signal so that the phase of the reference signal follows the change in the phase of the received signal accompanying the switching of the radiation pattern. The carrier reproduction circuit 310 controls the phase of the reference signal. By doing so, even if the radiation pattern of the broadcasting satellite 20 is switched, phase synchronization between the received signal and the reference signal can be ensured.

  In FIG. 3, the example in which the phase synchronization between the received signal and the reference signal is ensured by controlling the carrier recovery circuit 310 has been described, but the present invention is not limited to this. For example, the high frequency circuit 301 provided between the reception antenna 31 and the orthogonal demodulation circuit 314 may be provided with a configuration for ensuring phase synchronization between the reception signal and the reference signal.

  FIG. 4 is a diagram illustrating another example of the configuration of the receiver 32. FIG. 4 more specifically shows a configuration corresponding to the high-frequency circuit 301 in FIG.

  4 includes amplifiers 401, 403, 406, and 407, a phase shifter 402, a local oscillator 404, a mixer 405, a demodulation circuit 408, a memory 409, and a phase control unit 410. .

  A reception signal of the reception antenna 31 is input to the amplifier 401.

  The amplifier 401 amplifies the reception signal of the reception antenna 31 and outputs it to the phase shifter 402.

  The phase shifter 402 shifts the phase of the output signal of the amplifier 401 (the reception signal of the reception antenna 31) and outputs the result to the amplifier 403. The amount of phase shift by the phase shifter 402 is variable and is controlled by a phase control unit 410 described later.

  The amplifier 403 amplifies the output signal of the phase shifter 402 and outputs the amplified signal to the mixer 405.

  The amplifier 401, the phase shifter 402, and the amplifier 403 constitute a high frequency amplification unit 411 that amplifies the reception signal (broadcast wave) of the reception antenna 31.

  The local oscillator 404 outputs a local oscillation signal having a frequency corresponding to the selected station to the mixer 405.

  The mixer 405 mixes the output signal of the amplifier 403 and the local oscillation signal output from the local oscillator 404 and outputs the mixed signal to the amplifier 406.

  The local oscillator 404 and the mixer 405 constitute a channel selection unit 412 that converts the high frequency output from the high frequency amplification unit 411 into a desired intermediate frequency.

  The amplifier 406 amplifies the output signal of the mixer 405 and outputs the amplified signal to the amplifier 407. The amplifier 407 amplifies the output signal of the amplifier 406 and outputs the amplified signal to the demodulation circuit 408.

  The demodulating circuit 408 corresponds to the configuration subsequent to the orthogonal demodulating circuit 314 in FIG. However, in FIG. 4, a case where a configuration for ensuring phase synchronization between the received signal and the reference signal is provided in the high frequency circuit is described as an example. In this case, the demodulation circuit 408 may not include the memory 312 and the phase control unit 313 in FIG.

  When the received broadcast wave includes a switching notice signal, the demodulation circuit 408 outputs the switching notice signal to the phase control unit 410. In addition, when the broadcast wave includes phase information, the demodulation circuit 408 stores the phase information in the memory 409.

  When phase information is output from the demodulation circuit 408, the memory 409 stores the phase information. Further, the memory 409 stores the phase information when phase information is transmitted from the transmitter 12 through a communication path that does not pass through the broadcast satellite 20.

  When the switching notice signal is output from the demodulation circuit 408, the phase control unit 410 reads the phase information stored in the memory 409. Then, the phase control unit 410 controls the phase shift amount of the received signal by the phase shifter 402 based on the phase information read from the memory 409 at the timing indicated by the switching notice signal. Specifically, the phase control unit 410 controls the amount of phase shift of the received signal by the phase shifter 402 so as to cancel out the amount of change in the phase of the received signal due to switching of the radiation pattern. By doing so, phase synchronization between the received signal and the reference signal can be ensured.

  Although FIG. 4 has been described using an example in which the phase shifter 402 is provided between the amplifier 401 and the amplifier 403, the present invention is not limited to this. The position where the phase shifter 402 is provided may be between the input end of the received signal from the receiving antenna 31 and the demodulation circuit 408.

  FIG. 5 is a diagram illustrating still another example of the configuration of the receiver 32. In FIG. 5, the same components as those in FIG.

  The receiver 32 shown in FIG. 5 is different from the receiver 32 shown in FIG. 4 in that the phase shifter 402 is deleted, the phase shifter 501 is added, and the phase control unit 410 is replaced with the phase control unit 502. It is different from the point changed to.

  The phase shifter 501 is provided between the local oscillator 404 and the mixer 405, shifts the phase of the local oscillation signal output from the local oscillator 404, and outputs it to the mixer 405. The amount of phase shift by the phase shifter 501 is variable. The local oscillation signal whose phase is shifted by the phase shifter 501 and the output signal of the amplifier 403 are mixed by the mixer 405, so that the phase of the received signal is shifted. That is, shifting the phase of the local oscillation signal corresponds to shifting the phase of the reception signal.

  When the switching notice signal is output from the demodulation circuit 408, the phase control unit 502 reads the phase information stored in the memory 409. Then, the phase control unit 502 controls the phase shift amount of the local oscillation signal by the phase shifter 501 based on the phase information read from the memory 409 at the timing indicated by the switching notice signal. Specifically, the phase control unit 502 controls the phase shift amount of the local oscillation signal so that the phase of the signal after the synthesis with the local oscillation signal by the mixer 405 matches the phase of the reference signal. By doing so, phase synchronization between the received signal and the reference signal can be ensured.

  Note that the local oscillation signal output from the local oscillator 404 is an unmodulated signal. In general, shifting the phase of an unmodulated signal is easier than shifting the phase of a modulated signal having a frequency bandwidth (the received signal of the receiving antenna 31) (FIG. 4). Therefore, in the receiver 32 shown in FIG. 5, the circuit scale can be reduced as compared with the receiver 32 shown in FIG.

  Thus, according to the present embodiment, when the transmitter 12 switches the radiation pattern of the broadcast satellite 20, the transmitter 12 corresponds to the phase pattern of the broadcast wave received in the reception area corresponding to the radiation pattern after switching, and the radiation. A switching notice signal indicating the timing for switching the pattern is created. The receiving system 30 acquires the phase information and the switching notice signal generated by the transmitter 12, and at the timing indicated by the acquired switching notice signal, the phase of the received signal or the reference signal of the receiving antenna 31 based on the acquired phase information. To control.

  In this way, even if the radiation pattern is switched, phase synchronization between the reception signal of the reception antenna 31 and the reference signal can be ensured, so that occurrence of reception errors can be reduced.

  In addition, according to the present embodiment, the receiver 32 includes an orthogonal demodulation circuit 314 that performs orthogonal demodulation on the received signal of the reception antenna 31 using a reference signal, and an IQ generated by orthogonal demodulation by the orthogonal demodulation circuit 314. And a carrier regeneration circuit 310 that generates a reference signal based on the signal, and causes the carrier regeneration circuit 310 to control the phase of the reference signal based on the phase information at a timing indicated by the switching notice signal.

  In this way, even if the radiation pattern of the broadcast satellite 20 is switched, the phase of the reference signal can be made to follow the phase of the received signal.

  Further, according to the present embodiment, the receiver 32 includes a high frequency amplification unit 411 that amplifies the reception signal of the reception antenna 31, a local oscillator 404 that outputs a local oscillation signal having a frequency corresponding to the selected broadcast station, A mixer 405 that synthesizes the signal amplified by the high-frequency amplifier 411 and the local oscillation signal. In addition, according to the present embodiment, the high-frequency amplifier 411 is provided with the phase shifter 402 that shifts the phase of the received signal, and controls the amount of phase shift of the received signal by the phase shifter 402.

  In this way, even if the radiation pattern of the broadcasting satellite 20 is switched, the phase of the received signal can be made to follow the phase of the reference signal.

  Further, according to the present embodiment, the receiver 32 includes a high frequency amplification unit 411 that amplifies the reception signal of the reception antenna 31, a local oscillator 404 that outputs a local oscillation signal having a frequency corresponding to the selected broadcast station, A phase shifter 501 that shifts the phase of the local oscillation signal output from the local oscillator 404, and a mixer 405 that combines the signal amplified by the high-frequency amplifier 411 and the local oscillation signal whose phase is shifted by the phase shifter 501. The phase shifter 501 controls the phase shift amount of the local oscillation signal.

  In this way, even if the radiation pattern of the broadcasting satellite 20 is switched, the phase of the received signal can be made to follow the phase of the reference signal. Furthermore, the local oscillation signal is an unmodulated signal, and the phase shift of such an unmodulated signal is relatively easy. Therefore, an increase in the circuit scale of the receiver 32 can be suppressed.

  Further, according to the present embodiment, the transmitter 12 transmits a switching notice signal only a specified time before switching the radiation pattern of the broadcasting satellite.

  By doing so, it is possible to ensure the phase synchronization between the received signal and the reference signal when switching the radiation pattern of the broadcast satellite 20.

  Currently, it is normal for an administrator to determine the operation of a broadcasting satellite based on weather information in the broadcasting area. However, the control unit 14 may acquire the weather information of the broadcast area, and automatically determine whether or not the radiation pattern needs to be controlled based on the acquired information.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each means, each step, etc. can be rearranged so that there is no logical contradiction, and a plurality of means, steps, etc. can be combined or divided into one. .

DESCRIPTION OF SYMBOLS 1 Satellite broadcasting system 10 Transmission system 11 Transmission antenna 12 Transmitter 13 Communication part 14 Control part 20 Broadcasting satellite 21 Array feeding imaging reflector antenna 22 Horn antenna 23 Feeding circuit 24 Subreflector 25 Main reflector 30 Reception system 31 Reception antenna 32 Reception Machine 301 High-frequency circuit 302, 303, 405 Mixer 304, 305 A / D converter 306, 307 Root roll-off filter 308 Signal processing unit 309 Clock generation circuit 310 Carrier recovery circuit 311 90 ° phase shifter 312, 409 Memory 313, 410 , 502 Phase control unit 401, 403, 406, 407 Amplifier 402, 501 Phase shifter 404 Local oscillator 408 Demodulation circuit 411 High frequency amplification unit 412 Channel selection unit

Claims (10)

A broadcast satellite that relays and radiates phase-modulated broadcast waves;
A transmitter for controlling the radiation pattern of the broadcasting satellite;
A receiver that generates a reference signal from a received signal of a receiving antenna that receives a broadcast wave radiated from the broadcasting satellite, and demodulates the received signal based on the phase of the generated reference signal;
When the transmitter switches the radiation pattern of the broadcasting satellite, the transmitter notifies the phase information regarding the phase of the broadcast wave received in the reception area corresponding to the radiation pattern after the switching, and the switching notice indicating the timing of switching the radiation pattern. Create a signal and
The receiver acquires the phase information and the switching notice signal created by the transmitter, and at a timing indicated in the acquired switching notice signal, based on the acquired phase information, the received signal of the receiving antenna or A satellite broadcasting system, wherein the phase of the reference signal is controlled. A receiver that demodulates the received signal based on a phase of a reference signal obtained from a received signal of a receiving antenna that receives a broadcast wave radiated from a broadcasting satellite,
Phase information related to the phase of the received signal in the broadcast wave reception area, corresponding to the switched radiation pattern, and a switching notice signal indicating the timing for switching the radiation pattern, generated by the transmitter that controls the radiation pattern of the broadcasting satellite And a phase control unit that controls the phase of the reception signal of the reception antenna or the reference signal based on the acquired phase information at the timing indicated in the acquired switching advance notice signal. Receiving machine. The receiver according to claim 2, wherein
An orthogonal demodulation circuit that performs orthogonal demodulation on the received signal of the receiving antenna using the reference signal;
A carrier recovery circuit that generates the reference signal based on an IQ signal generated by orthogonal demodulation by the orthogonal demodulation circuit;
The phase control unit causes the carrier recovery circuit to control the phase of the reference signal based on the phase information. The receiver according to claim 2, wherein
A high-frequency amplifier for amplifying a reception signal of the reception antenna;
A local oscillator that outputs a local oscillation signal having a frequency corresponding to the selected broadcast station;
A mixer that synthesizes the signal amplified by the high-frequency amplifier and the local oscillation signal;
The high-frequency amplifier is provided with a phase shifter that shifts the phase of the received signal,
The phase control unit controls a shift amount of a phase of the reception signal by the phase shifter based on the phase information. The receiver according to claim 2, wherein
A high-frequency amplifier for amplifying a reception signal of the reception antenna;
A local oscillator that outputs a local oscillation signal having a frequency corresponding to the selected broadcast station;
A phase shifter for shifting the phase of the local oscillation signal output from the local oscillator;
A mixer that synthesizes the signal amplified by the high-frequency amplifier and the local oscillation signal shifted by the phase shifter;
The phase control unit controls a phase shift amount of the local oscillation signal by the phase shifter based on the phase information. The receiver according to any one of claims 2 to 5,
A receiver characterized in that the switching notice signal and the phase information are acquired via a predetermined communication path via the broadcast satellite or not via the broadcast satellite, respectively. A transmitter for controlling a radiation pattern of a broadcasting satellite that relays and emits a phase-modulated broadcast wave,
When switching the radiation pattern of the broadcasting satellite, the phase information related to the phase of the broadcast wave received in the reception area corresponding to the radiation pattern after the switching and the switching notice signal indicating the timing of switching the radiation pattern are created. A control unit;
Communication that transmits the phase information and switching notice signal created by the control unit to the broadcasting satellite, or to a receiver that demodulates the broadcasting wave via a predetermined communication path that does not pass through the broadcasting satellite. And
A transmitter characterized by comprising: The transmitter of claim 7, wherein
The control unit causes the communication unit to transmit the switching notice signal only a specified time before switching the radiation pattern of the broadcasting satellite. A receiving method in a receiver that demodulates the received signal based on a phase of a reference signal obtained from a received signal of a receiving antenna that receives a broadcast wave radiated from a broadcasting satellite,
Phase change information generated by a transmitter for controlling the radiation pattern of the broadcasting satellite, corresponding to the radiation pattern after switching, and phase information regarding the phase of the broadcast wave received in the reception area, and a switching notice signal indicating the timing for switching the radiation pattern And a step of obtaining
Controlling the phase of the reception signal of the reception antenna or the reference signal based on the acquired phase information at the timing indicated in the acquired switching advance notice signal;
Including receiving method. A transmission method in a transmitter for controlling a radiation pattern of a broadcasting satellite that relays and radiates a phase-modulated broadcast wave,
When switching the radiation pattern of the broadcasting satellite, the phase information related to the phase of the broadcast wave received in the reception area corresponding to the radiation pattern after the switching and the switching notice signal indicating the timing of switching the radiation pattern are created. Steps,
Transmitting the created phase information and switching notice signal to the broadcast satellite, respectively, or transmitting to a receiver that demodulates the broadcast wave via a predetermined communication path not passing through the broadcast satellite;
Including sending method.